Writing a letter is a very good preparation for an internship or job interview. It is your first step in showing a specific company what you can and want to do for them.

You must keep in mind that application letters, wheter its is for an internship or a job, should not be longer than one page. And should follow the standart 4-paragraph format:

State that you're applying for the placement (phrase the placement title as your source phrased it). Tell where you learned about the placement (ad, referral, etc.). Include any reference number mentioned in the ad. Briefly show that you have the major qualifications required by the ad: a college degree, professional certification, job experience, etc. Summarize your other qualifications briefly in the same order in which you plan to discuss them in the letter.

Develop your major qualifications in detail. Be specific about what you've done; relate your achievements to the work you'd be doing in this new job. Remember that readers know only what you tell them. This is not the place for modesty!

Develop your other qualifications, even it the ad doesn't ask for them. (If the ad asks for a lot of qualifications, pick the most important three or four.) Show what separates you from the other applicants who will also answer the ad. Demonstrate your knowledge of the organization.

Ask for an interview; tell when you'll be available to be interviewed and to begin work. End on a positive, forward-looking note.

When doing it by Email:
Some Web ads give you a street address to submit applications but say "e-mail preferred." Other ads just give an e-mail address. No research exists on whether e-mail application letters should be shorter than paper ones. Until we know which works better, you have two choices: paste a traditional letter into your e-mail screen, or edit your letter to create a shorter, one-screen letter. To make your application letter professional:

Put the placement number or title for which you're applying in your subject line and in the first paragraph. Prepare your letter in a word-processing program with a spell checker to make it easier to edit and proof the document. Use a standard font (Times Roman, Palatino, or Helvetica) in 11- or 12-point type. Don't send anything in all capital letters.

Don't use smiley faces or other emoticons

Edit the letter carefully and proof it several times to make sure it' s perfect. Errors suggest that you're careless or inept.

Use a lively, energetic style that makes you sound like a real person.

Be positive. Don't plead (“Please give me a chance”) or apologize (“l cannot promise that I am substantially different from the lot”). Most negatives should be omitted in the letter.

Create you-attitude by describing exactly what you have done and by showing how that relates to what you could do for this employer. (Lacks you-attitude: "I want a job with your company." You attitude: "I would like to apply for Procter & Gamble's management trainee program.")

Keep your first and last paragraphs fairly short-preferably no more than four or five typed lines. When you have a long paragraph, check to be sure that it covers only one subject. If it covers two or more subjects, divide it into two or more paragraphs. If a short paragraph covers several subjects, consider adding a topic sentence to provide paragraph unity.

Always use at least a full page. A short letter throws away an opportunity to be persuasive; it may also suggest that you have little to say for yourself or that you aren't very interested in the placement. Employers don't want longer letters, but they will read them if the letter is well written and if the applicant establishes early in the letter that he or she has the credentials the company needs.

Extra Tips

Always focus on major requirements of the internship or job offer for which you're applying.

Give relevance to the points that separate you from other applicants

Focus on points that show your knowledge of the organization and the position

Remark qualities that every employer is likely to value: ability to write and speak effectively, solve problems, get along with people